Subscribers of mobile network operators are allowed or not to roam in a specific area depending on roaming agreements with other operators and, in particular, depending on information stored in the subscriber profile.
Generally speaking, where a subscriber attempts to connect to a mobile network owned by an operator lacking a roaming agreement with the operator of said subscriber, and the subscriber thus prevented for roaming therein, the operation ‘Update Location’ fails and the subscriber cannot make or receive calls other than emergency calls.
At present, there are operators, hereinafter referred to as roamer's operators, which can perform a Location Update procedure for a subscriber via a so-called Local Number Server under an invoice agreement with the subscriber himself. Under this approach, and even where the subscriber is roaming in an area without roaming agreement with the subscriber's operator, the Local Number Server is enabled to produce a Location Update success as Location Update result, providing the roaming subscriber with a temporary own Mobile Station Integrated Services Digital Network number (hereinafter MSISDN) and allowing said subscriber to make and receive calls.
In particular, the Local Number Server (hereinafter LNS) may be enabled to change an unsuccessful Location Update result in a Location Update success, providing to the roaming subscriber a temporary own MSISDN and allowing him to make and receive calls.
This temporary own MSISDN is registered along with other temporary subscription data in a so-called Roaming Location Server (hereinafter RLS) assigned to hold necessary subscriber and subscription data for the roaming subscriber whilst said roaming subscriber is roaming in the area served by said LNS and whilst the invoice agreement with the roaming subscriber is actively valid, that is, whilst the roamer's operator gets incomes from the roaming subscriber for allowing said roaming subscriber make and receive calls in the area served by the LNS.
The RLS assigned to hold necessary subscriber and subscription data for the roaming subscriber behaves as a Home Location Register (hereinafter HLR) or as a Home Subscriber Server (hereinafter HSS) would do in the visited network owned by the roamer's operator, depending on the configuration and services of said visited network; and, likewise, the RLS provides the necessary subscriber and subscription data for the roaming subscriber to any visited serving entity (hereinafter VSE) of a visited network where the subscriber may be allowed to roam, and the VSE thus serving the roaming subscriber.
In this situation, the subscriber's operator loses revenues derived from not having roaming agreements with the roamer's operator, whilst said roamer's operator is getting revenues from the subscriber by using the subscriber's operator Subscriber Identity Module (generally abbreviated as SIM) or a newer generation of operator's card.